Category: Metal geometry shader


Metal is the standard graphics API for Apple devices. See the advantages and disadvantages of using Metal below. Metal does not support geometry shaders A small script that contains the mathematical calculations and algorithms for calculating the Color of each pixel rendered, based on the lighting input and the Material configuration.

More info See in Glossary. Or, if you are using MacOS, open Terminal and use the -force-gfx-metal command line argument.

metal geometry shader

Xcode offers Metal API validation, which you can use to trace obscure issues. Note : Enabling validation increases CPU usage, so only enable it for debugging. Metal allows you to select a GPU device when you run your application. Metal allows you to use memory-less render targets to optimize memory on mobile devices introduced in iOS and tvOS This enables you to render to a RenderTexture without backing it up in system memory, so contents are only temporarily stored in the on-tile memory during rendering The process of drawing graphics to the screen or to a render texture.

By default, the main camera in Unity renders its view to the screen. For more information, see RenderTexture. Version: Language : English. Unity Manual. Unity User Manual OpenGL Core. Publication Date: Optimize graphics and compute performance with kernels that are fine-tuned for the unique characteristics of each Metal GPU family.

The Metal Performance Shaders framework contains a collection of highly optimized compute and graphics shaders that are designed to integrate easily and efficiently into your Metal app. These data-parallel primitives are specially tuned to take advantage of the unique hardware characteristics of each GPU family to ensure optimal performance.

Apps adopting the Metal Performance Shaders framework achieve great performance without needing to create and maintain hand-written shaders for each GPU family. A texture for use in convolutional neural networks that stores transient data to be used and discarded promptly.

Support dynamic scenes and denoising by extending your ray tracer with Metal Performance Shaders. The base class for data structures that are built over geometry and used to accelerate ray tracing. Language: Swift Objective-C. Framework Metal Performance Shaders.

Geometry Shader

SDKs iOS 9. Overview The Metal Performance Shaders framework contains a collection of highly optimized compute and graphics shaders that are designed to integrate easily and efficiently into your Metal app.

The Metal Performance Shaders framework supports the following functionality: Apply high-performance filters to, and extract statistical and histogram data from images.

Implement and run neural networks for machine learning training and inference. Solve systems of equations, factorize matrices and multiply matrices and vectors. Accelerate ray tracing with high-performance ray-geometry intersection testing. Topics Fundamentals. Article Tuning Hints. Device Support. Image Filters. API Collection Image Filters Apply high-performance filters to, and extract statistical and histogram data from images. Neural Networks. Implement and run deep learning using previously obtained training data.Geometry shaders are not supported in Metal 2.

What's your use case? I think these shaders could be implmented using compute kernels. You would emulate the vertex shader with a compute kernel by writing what a vertex shader normally outputs to a buffer.

Then read that in with a second compute kernel emulating this geometry shader writing out the wide version of the vertices to another buffer. Finally you render using a passthrough vertex shader with the vertices created by your second compute kernel. Ok thanks I will give it a shot.

I don't know much about how compute kernels work yet. Do you know of any simple online examples of this kind of multi-stage rendering?

Shader Compilation Target Levels

Hey, I am not Dan, but I believe you don't need to emulate geometry shaders for relatively simple stuff like drawing of the thick lines. Thing is, for thick lines you know number of vertices in advance - for example if you're drawing them as single triangle strip, you'll need two times the line vertices. If as a quad two-triangle strip you'll need 4 vertices per line segment, and so on.

We discussed doing wide lines efficiently just a few weeks ago. Check it out. OK thanks I will check this out. Maybe not - maybe the extra compute passes would be worse than submitting 4x the data. I have not enough experience with shader programming yet. Then you ask Metal to draw as many instances of 4-vertex triangle strips quads as number of segments you draw.

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Please enter a title.Discussion in ' Shaders ' started by tillFeb 27, Search Unity. Log in Create a Unity ID. Unity Forum. Forums Quick Links.

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Asset Store Spring Sale starts soon! Move vertices: geometry shader vs compute shader aka Metal does not have geom shader? Joined: Feb 27, Posts: 8. Hello Unity community, hello forum! I am new here and am learning Unity. I do have some "fixed pipeline OpenGL background" and a fair theoretical understanding of modern shaders having read two OpenGL books.

In other words: a spare time Unity noob but with a strong software engineering background. I am rendering a square tileable "infinite" mesh world size N by N.

When the player's rigid body crosses either side the player is teleported back at the opposite side. I was hoping that Unity would somehow - automagically - translate the geometry shader into whatever Metal would do here, in order to move the triangles.

Unfortunately all I get is an "unsupported shader" and a pink texture. I am still on Mac Sierra But it didn't work on iOS So my question: what would be the other best way to "visually" make the mesh repeat itself around the actual game area? So that solution does not seem too attractive. But all I know about compute shaders that I can transfer data buffers to the GPU, have it compute whatever function and the result typically comes back to the CPU. Or would the mesh end up twice in VRAM?

Move vertices: geometry shader vs compute shader (aka Metal does not have geom shader)?

Last edited: Feb 27, Here's an image which illustrates my current geometry shader approach: the cyan, pink and yellow colours indicate whether the corresponding triangle had been moved along the X- Z- or both X- and Z- axes, depending on its distance to the world camera which is an extremely simple calculation: simply subtract the X and Z components respective of each vector, no Euklidean distance computation required.

Repeating Landscape. Joined: Dec 7, Posts: 8, Apple put devs in a bit of a rock and a hard place by refusing to support more modern OpenGL versions that support compute shaders. Metal, as you've found, does not support geometry shaders, but does support compute shaders.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The dark mode beta is finally here.

Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I'm trying to implement voxel cone tracing in Metal. One of the steps in the algorithm is to voxelize the geometry using a geometry shader. Metal does not have geometry shaders so I was looking into emulating them using a compute shader. I pass in my vertex buffer into the compute shader, do what a geometry shader would normally do, and write the result to an output buffer.

I also add a draw command to an indirect buffer. I use the output buffer as the vertex buffer for my vertex shader. This works fine, but I need twice as much memory for my vertices, one for the vertex buffer and one for the output buffer.

metal geometry shader

Is there any way to directly pass the output of the compute shader to the vertex shader without storing it in an intermediate buffer? I don't need to save the contents of the output buffer of the compute shader. I just need to give the results to the vertex shader. For each triangle, I need to output a triangle with vertices at these new positions instead. The triangle vertices come from a vertex buffer and is drawn using an index buffer. I also plan on adding code that will do conservative rasterization just increase the size of the triangle by a little bit but it's not shown here.

Currently what I'm doing in the Metal compute shader is using the index buffer to get the vertex, do the same code in the geometry shader above, and outputting the new vertex in another buffer which I then use to draw.

Here's a very speculative possibility depending on exactly what your geometry shader needs to do. I'm thinking you can do it sort of "backwards" with just a vertex shader and no separate compute shader, at the cost of redundant work on the GPU.

You would do a draw as if you had a buffer of all of the output vertices of the output primitives of the geometry shader. You would not actually have that on hand, though.

You would construct a vertex shader that would calculate them in flight. So, in the app code, calculate the number of output primitives and therefore the number of output vertices that would be produced for a given count of input primitives. Do a draw of the output primitive type with that many vertices. You would not provide a buffer with the output vertex data as input to this draw. You would provide the original index buffer and original vertex buffer as inputs to the vertex shader for that draw.

The shader would calculate from the vertex ID which output primitive it's for, and which vertex of that primitive e. From the output primitive ID, it would calculate which input primitive would have generated it in the original geometry shader. The shader would look up the indices for that input primitive from the index buffer and then the vertex data from the vertex buffer.

This would be sensitive to the distinction between a triangle list vs. It would apply any pre-geometry-shader vertex shading to that data.Geometry shaders reside between the Vertex Shaders or the optional Tessellation stage and the fixed-function Vertex Post-Processing stage. Geometry shader invocations take a single Primitive as input and may output zero or more primitives. There are implementation-defined limits on how many primitives can be generated from a single GS invocation.

GS's are written to accept a specific input primitive type and to output a specific primitive type. While the GS can be used to amplify geometry, thus implementing a crude form of tessellation, this is generally not a good use of a GS.

metal geometry shader

The main reasons to use a GS are:. In OpenGL 4. One was the ability to write to multiple output streams.

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This is used exclusively with transform feedback, such that different feedback buffer sets can get different transform feedback data. The other feature was GS instancing, which allows multiple invocations to operate over the same input primitive. This makes layered rendering easier to implement and possibly faster performing, as each layer's primitive s can be computed by a separate GS instance.

Each geometry shader is designed to accept a specific Primitive type as input and to output a specific primitive type. The accepted input primitive type is defined in the shader:. If Tessellation is enabled, then the primitive type is specified by the Tessellation Evaluation Shader 's output qualifiers.

If Tessellation is not enabled, then the primitive type is provided by the drawing command that renders with this shader program. These work exactly the same way their counterpart OpenGL rendering modes do. To output individual triangles or lines, simply use EndPrimitive see below after emitting each set of 3 or 2 vertices.

The number must be a compile-time constant, and it defines the maximum number of vertices that will be written by a single invocation of the GS. The minimum value for this limit is See the limitations below. The GS can also be instanced this is separate from instanced renderingas this is localized to the GS.

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This causes the GS to execute multiple times for the same input primitive. This is useful for layered rendering and outputs to multiple streams see below. To use instancing, there must be an input layout qualifier :.GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together.

metal geometry shader

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